“You can’t do it within national borders, polluted water flows from one country to another, polluted air flows from one country to another – we have got to protect wildlife.

“There’s no point protecting the feeding grounds of winter migratory birds if someone down the flight line is shooting them all. You have to work together to do things”.

But Vote Leave Cymru’s Matthew Mackinnon said: “This is half-hearted stuff from Jeremy Corbyn and doesn’t stand up to any kind of scrutiny at all – for starters, there is no such thing as EU money and the cost to Britain for membership of the EU is around £10 billion a year net.

“Just imagine what our share of that money could be spent on here in North Wales, improving infrastructure, creating regeneration projects and supporting Welsh farmers.

He added: “In the end, Welsh voters will see through the negativity of the project fear campaign and will opt for a more positive vision for Britain’s future outside of the EU.

“Given Jeremy Corbyn’s long held views on the EU it is a surprise and a disappointment that he hasn’t got the courage to back us in achieving that.”